Traditional non-smart cellphones have been replaced with the emergence of smart cellphones. Additionally, screen sizes of the cellphones are increasing. Operation of the cellphones has also changed from a traditional push-button mode to a touch pressure control mode. Thereafter, touch pressure control techniques are rapidly developing.
Touch pressure control is carried out by pressing a touch control panel of a cellphone or tablet computer. As surface of the touch control panel deforms, the deformation would cause variation of capacitance or resistance, which can be detected by a pressure sensor to achieve sensing of touch pressure. This technical scheme effectively achieves sensing of touch pressure. However, the touch control layer is integrated within the display panel, and it generates interference among touch control signals. Conventionally, to solve this problem, an add-on type structure for carrying out the touch pressure control is adopted. But, because there is an air layer at the upper side and the lower side of the pressure sensors, this makes lower sensitivity of touch pressure. Moreover, a new substrate has to be introduced into the process of producing the pressure sensors. However, addition of attaching times and additional flexible circuit boards both increase costs of manufacturing display panel. Also, after the pressure sensors are attached to the display panel, thickness and weight of the entire display module are increased, which does not allow for thin thickness and light weight sought by the cellphone and mobile working. It is not the most satisfactory technical scheme for carrying out touch pressure control.
In view of the foregoing, the conventionally-used add-on type of touch pressure control panel has a lower sensitivity of sensing touch pressure, and the manufacturing process thereof needs additional devices which increases the weight and thickness of the panel and makes it difficult to accomplish a built-in type of touch pressure control panel with high quality.